Discussion: “Convection Heat Transfer of Power-Law Fluids Along the Inclined Nonuniformly Heated Plate With Suction or Injection” [Sui, J., Zheng, L., and Zhang, X., 2016, ASME J. Heat Transfer, 138(2), p. 021701]

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Asterios Pantokratoras
Keyword(s):  
Heat Transfer ◽  
Power Law ◽  
Convection Heat Transfer ◽  
Heated Plate ◽  
Convection Heat ◽  
Power Law Fluids ◽  
Suction Or Injection

The present comment concerns some doubtful results in the above paper.

Convection Heat Transfer of Power-Law Fluids Along the Inclined Nonuniformly Heated Plate With Suction or Injection

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Jize Sui ◽  
Liancun Zheng ◽  
Xinxin Zhang
Keyword(s):  
Heat Transfer ◽  
Prandtl Number ◽  
Skin Friction ◽  
Power Law ◽  
Inclination Angle ◽  
Convection Heat Transfer ◽  
Heated Plate ◽  
Convection Heat ◽  
Power Law Fluids ◽  
Suction Or Injection

A comprehensive analysis to convection heat transfer of power-law fluids along the inclined nonuniformly heated plate with suction or injection is presented. The effects of power-law viscosity on temperature field are taken into account in highly coupled velocity and temperature fields. Analytical solutions are established by homotopy analysis method (HAM), and the effects of pertinent parameters (velocity power-law exponent, temperature power index, suction/injection parameter, and inclination angle) are analyzed. Some new interesting phenomena are found, for example, unlike classical boundary layer problem in which the skin friction monotonically increases (decreases) with suction increases (injection increases), but there exists a special region where the skin friction is not monotonic, which is strongly bound up with Prandtl number, which have never been reported before. The nonmonotony occurs in suction region for Prandtl number Npr < 1 and injection region for Npr > 1. Results also illustrate that the velocity profile decreases but the heat convection is enhanced obviously with increasing in temperature power exponent m (generalized Prandtl number Npr has similar effects), the decreases in inclination angle lead to the reduction in convection and heat transfer efficiency.

Forced convection heat transfer study of a blunt-headed cylinder in non-Newtonian power-law fluids

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jaspinder Kaur ◽  
Roderick Melnik ◽  
Anurag Kumar Tiwari
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Drag Coefficient ◽  
Power Law ◽  
Average Nusselt Number ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Total Drag ◽  
Shear Thinning Fluids ◽  
Power Law Fluids

Abstract In this present work, forced convection heat transfer from a heated blunt-headed cylinder in power-law fluids has been investigated numerically over the range of parameters, namely, Reynolds number (Re): 1–40, Prandtl number (Pr): 10–100 and power-law index (n): 0.3–1.8. The results are expressed in terms of local parameters, like streamline, isotherm, pressure coefficient, and local Nusselt number and global parameters, like wake length, drag coefficient, and average Nusselt number. The length of the recirculation zone on the rear side of the cylinder increases with the increasing value of Re and n. The effect of the total drag coefficient acting on the cylinder is seen to be higher at the low value of Re and its effect significant in shear-thinning fluids (n < 1). On the heat transfer aspect, the rate of heat transfer in fluids is increased by increasing the value of Re and Pr. The effect of heat transfer is enhanced in shear-thinning fluids up to ∼ 40% and it impedes it’s to ∼20% shear-thickening fluids. In the end, the numerical results of the total drag coefficient and average Nusselt number (in terms of J H −factor) have been correlated by simple expression to estimate the intermediate value for the new application.

Unsteady Forced Convection Heat Transfer for Power Law Fluids in a Pipe

2010 ◽  
Author(s):  
Botong Li ◽  
Liancun Zheng ◽  
Xinxin Zhang
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Power Law ◽  
Control Volume ◽  
Convection Heat Transfer ◽  
Inlet Temperature ◽  
Convection Heat ◽  
Forced Convection Heat Transfer ◽  
Power Law Fluids ◽  
Power Law Index

This paper studied the problem of forced convection heat transfer for power law fluids in a pipe which was affected by the varying inlet temperature. The fluid flow was hydrodynamically fully-developed and laminar while the effects of viscous dissipation and the power law kinematic viscosity on heat transfer were considered. A control volume technique based on the finite difference model coupled with the LU decomposition method was adopted and the least squares polynomial was introduced to approximate the non-linear items. The results show that the heat transfer behaviors are strongly depending on the value of the power law index. It is found that the thermal wave of the inlet temperature has less penetration with the increasing axial coordinate, and the effect of heat transfer is dominant away from the wall. The temperature profile is flatter as the power law index increases, which is implies that the shear-thickening non-Newtonian flows are affected easier by the inlet temperature than the shear-thinning fluids.

Magnetohydrodynamics Thermocapillary Marangoni Convection Heat Transfer of Power-Law Fluids Driven by Temperature Gradient

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Yanhai Lin ◽  
Liancun Zheng ◽  
Xinxin Zhang
Keyword(s):  
Heat Transfer ◽  
Temperature Gradient ◽  
Differential Equations ◽  
Power Law ◽  
Numerical Solutions ◽  
Marangoni Convection ◽  
Convection Heat Transfer ◽  
Temperature Fields ◽  
Convection Heat ◽  
Power Law Fluids

This paper presents an investigation for magnetohydrodynamics (MHD) thermocapillary Marangoni convection heat transfer of an electrically conducting power-law fluid driven by temperature gradient. The surface tension is assumed to vary linearly with temperature and the effects of power-law viscosity on temperature fields are taken into account by modified Fourier law for power-law fluids (proposed by Pop). The governing partial differential equations are converted into ordinary differential equations and numerical solutions are presented. The effects of the Hartmann number, the power-law index and the Marangoni number on the velocity and temperature fields are discussed and analyzed in detail.

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